Teaching meiosis, while I find to be fascinating, is always really, really hard to teach. I plan to outline a few things in this post and hope you may find something that will help you in your teaching journey.
First, I ask students if every cell in their body has the same # of chromosomes or amount of DNA. Most of them say yes. So probing a bit more, we will come to the conclusion that sex cells (gametes) only have 1/2 the number of chromosomes. I tell them we get these cells by dividing twice, instead of once like they do in mitosis.
Then I ask them if they think sperm are all identical or eggs, are they are all identical? Do we look exactly like our siblings? Then I tell them that is part of the dividing process too, there are processes that have to occur to make sure that our sperm and egg cells aren't exactly like each other. We write out a simplified diagram of meiosis and then another diagram of what crossing over is. This is the introduction to one of my most favorite activities, pigeon meiosis! This website, https://learn.genetics.utah.edu/content/pigeons/, has quite a few other genetics activities with pigeons. Here is the activity that I use. I have made some edits so that it works with my personal class timing and setup. This activity does a great job of introducing crossing over and fertilization. It works really well as an introduction to meiosis.
Pigeon Directions: Slideshow to use to walk through the activity with your students
Pigeon Directions + Questions: This is the student document students use that has the directions and questions to answer as they move through the activity
Pigeon Chromosomes and Pigeon Offspring Worksheet: You need these to complete the activity
Day 2 of teaching Meiosis is used to diagram out each specific phase and write descriptions of the phase and label any major structures. Here is the notes page that I created. I use pink and blue to represent chromosomes and make sure to keep my color coding really specific throughout so students can easily follow the color changes through crossing over and how they end up in the final gametes.
Before the notes or after, I like to show a video showing the process. Here are a few that I like:
Day 3-4 are saved for student led modeling. Every year when I start this assignment, a little anxiety sets in. The kids have a hard time getting going, they ask a ton of questions, and at first it seems like it is impossible and they are never going to figure it out....that being said, kids need to do hard things. I've added new directions, I've changed how I walk them through it and in the end, the content is hard and I think they will always struggle...at first. I am going to post my assignment, all feedback is welcome, but just know....when they are done, they will have a better understanding and that is what matters.
The modeling assignment uses real traits that are coded on a single gene, I really wanted it to feel more accurate. They used pipe cleaners and beads to represent the genes. The beads are then coded with the specific allele. They have 2 autosomes and 1 pair of sex chromosomes (an X and Y). They take those items and the giant whiteboards I have, and they model each phase of meiosis. They take a picture of their stage and put it in a google slides presentation, and answer some questions at the end. Here it is for you to take a look. Would love to hear any modifications you make and your results.
Usually after this we give a quiz or like this year, we won't have time so we will move on to mendelian genetics. Meiosis will be assessed on the unit test. I hope you can find something useful and would love to hear any thoughts or questions you may have.
Happy teaching!
Mrs. Townsend
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